[evolution] String freeze break plea for gnome-43 branch

[Milan Crha <mcrha redhat com>]

        Hello,
I'd like to ask for a string freeze break approval for the 'evolution'
project for the gnome-43 branch in order to apply change for [1] to it.

Background: there had been added use of header bars (client side
decorations) on the most used windows of the application for the .beta
GNOME release. I've been told by multiple users on various channels for
an option to turn the header bars off. There was no such option until
the [1]. Even I agree with Andre that such claims are not a good excuse
for a code complexity (he wrote it in the [1]), I can understand the
header bars can mean a bad experience to some users.

There had been added only two options into GSettings, which have
translatable the <summary> and <description>. It's a hidden option and
the default is to use the header bars, thus there's no difference on
the UI side with compare to the 3.46.0 release.

I returned back one string, "%s — Evolution", which had been removed
when the change landed. I guess neither this one causes a problem, but
if needed, I can remove this string for the gnome-43 branch.

That being said, I believe it's safe to include the change. The
GSettings strings are hidden, thus may not cause any disruption in the
GUI for regular users. The added functionality will help to those whom
do not need header bars, which is a plus, from my point of view.

        Bye,
        Milan

[1] https://gitlab.gnome.org/GNOME/evolution/-/issues/2039